The present invention relates to a video color printer, more particularly to a method and a circuit for preventing irregularities of the color printing position generated by overlapping of the drive timing of a drum over the drive timing of a thermal print head, in a heating-transcription video color printer of non-impact type.
Conventional heating-transcription video color printer is operated by means of heating of a thermal print head according to image signals of red R, green G and blue B, whereby three colors, which are yellow Y, magenta M and cyan C, are printed one by one based on the given order. The process of printing of one color among them is followed. One line is printed through the heating of the thermal print head in the static state of drum. After printing the one line of the given color, the drum is driven by a stepping motor, to be shifted to the next line in order to print the next line of the given color. After printing the given color on the given number of lines in the manner described above, the driving of the drum makes another color be printed on initial printing position of the given color in the same manner as described above. That is, the printing of the whole image is constituted of the serial print steps of Y, M and C color.
In the above printer, however a driving-timing of the drum operated by the rotation of the stepping motor may be not coincident with a heating-timing of the thermal print head. Thus the printing positions of the three colors become irregular on the initial printing positions and on the each of the line positions. That is, conventional printer has a problem that if the heating of the thermal print head happens in the state of the rotation of the drum, the color imprinting operation of the image makes a sliding phenomena on the picture, and thus provides a deteriorated picture quality to the video color printer.